The Velké jeřábí jezero NNR - Great Crane Lake covers a territory of 29.9 ha at elevations of 921 - 938 metres in the parish of Přebuz. It was declared a reserve in 1993 and the subject of the protection is a typical mountain raised peatbog, partly covered with dwarf pine stands and scattered spruces. The forest-free areas are covered with moss growths and numerous pools. This is one of the most valuable peatbogs in the Krušné hory mountain range for its wealth of animal and plant species but also for its undisturbed condition as it demonstrates all of the development phases of raised peatbogs on the mountain watershed.
The Velké jeřábí jezero NNR is a mountain watershed raised peatbog. The geological basement consists of medium-grained muscovite-biotite granite of the Krušnohorský type, with biotite granite in the eastern section. These rocks are covered by a soil mantle of granite colluvial type between 1 and 2 metres thick. The peatbog is formed of two seams of peat. The northern seam lies in the north and centre of the reserve and also across the state border in Germany. The southern seam is smaller and was disturbed by peat extraction in the past. The total area of peat is estimated to be 36 ha and the peat is around 170 cm in depth.
Plant species found around the pools include the characteristic mosses – the Warrnstorfia moss (Drepanocladus fluitans), and Sphagnum cuspidatum. These mosses grow into a thick cushion which fills up the water areas and later allows further stages of peatbog development to begin, such as colonisation by bog sedge (Carex limosa). The insectivorous plants which grow along the banks of the bog pools are the round-leaved sundew (Drosera rotundifolia), great sundew (Drosera anglica) and the hybrid sundew (Drosera x obovata). The varied communities growing on the emerald-green mossy carpet (Sphagnum sp.) include the cranberry (Oxyccocus palustris) with its red berries and the bog rosemary (Andromeda polifolia) with its pink and white flowers. In places there are abundant populations of the liverwort Gymnocolea inflata. The vegetation mosaic on the peatbogs includes dwarf pines (Pinus rotundata), the mosses Sphagnum magellanicum and Sphagnum molluscum as well as common cottongrass (Eriophorum angustifolium) and few-flowered sedge (Carex pauciflora). In areas of the bog with lower moisture levels (due to a fall in the groundwater level or the peat layer growing upwards), these raised areas develop growths of the moss Polytrichum strictum, cup lichens from the Cladonia order, heather (Calluna vulgaris) and hare’s-tail cottongrass (Eriophorum vaginatum).
The large mammals red deer (Cervus elaphus), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) inhabit the area and we can also find the pygmy shrew (Sorex minutus), common shrew (Sorex araneus) and the field vole (Microtus agrestis) from the smaller mammals. Due to the higher proportion of spruces than the nearby Velký močál NNR, Velké jeřábí jezero NNR offers more favourable nesting conditions for certain bird species, such as the three-toed woodpecker (Picoides tridactylus). Significant populations of capercaillie (Tetrao urogallus) and black grouse (Tetrao tetrix) live in the area around the peatbogs. Other more common birds which have been observed on the territory include the snipe (Gallinago gallinago), honey buzzard (Pernis apivorus), hobby (Falco subbuteo), wryneck (Jynx torquilla), red-backed shrike (Lanius collurio) and great grey shrike (Lanius excubitor).